Electronic timer



June 29, 1948. J. w. LAURICEELLA ELECTRONIC TIMER Filed A ril 25, 1947' "Patented June 29, 1948 ELECTRONIC TIMER John William Lauricella, Pascale, N. 1., allignor to Bendix Aviation Corporation, N. J a corporation of Delaware Tcterboro,

Application April 23, 1947, Serial No. 743,304

'1 Claims. (01. 171-91) The invention relates to improvements in electrical timing apparatus of the type disclosed in the copending application Serial No. 607,736, filed July 30, 1945 by Dwight Wilson Bloser and more particularly to that type of timing apparatus wherein a series of load devices are sequentially operated for a predetermined time and there is automatically provided a predetermined interval of time between cycles of operation.

An object of the invention is to provide improved electrical timing apparatus controlled by the charged condition of a capacitor or condenser.

Another object of theinvention is to provide an electronic timer'of the type described in which a charging circuit for the capacitor is completed through the grid and cathode of an electronic control valve.

Another object of the invention is to provide a novel relay switch having the double function of closing the charging circuit of the capacitor and the energizing circuit of a stepper relay.

Another object of the invention is to arrange the latter relay switch so as to effect a discharging circuit for the capacitor upon opening and the shifting of the stepper switch.

Another object of the invention is to provide an electronic timer having a stepper relay and a novel operator-controlled switch efiective for shunting the electronic valve so that during operation of said timer, the stepper switch may at will be returned to a predetermined home position.

Another object of the invention is to provide improved timing apparatus for controlling the periods of inflation of a series of solenoid controlled infiatable elements or boots for preventing the accumulation of ice on or the removal of ice from aerofoil surfaces of an aircraft. The

latter system of inflatable elements may be of the not designed as a definition of the limits of the invention, reference being had to the appended claims for this purpose.

The drawing is a diagrammatic view illustrata system for timing the operation of a stepper relay 10 which controls the energization of a series of loads ll, indicated as a plurality of electromagnets. The electronic timer is particularly adapted for use in conjunction with the manifold type of inflatable ice eliminating systems described in the aforenoted copending application. The electromagnets ll may serve upon energization to open the boot-inflating valves automatically in the proper sequence and for proper time intervals.

The stepper relay it may be of a conventional type comprising an electromagnetic winding 12 which controlsthe movement of an armature I3 plvotally supported at H. A ratchet arm 55 is pivotally mounted on the armature l3 and is biased into engaging relation with a ratchet wheel i6 by a spring ii, A second spring 18 biases the armature i3 in a counterclockwise direction into contacting relation with a stop IS. A pawl 20 is biased into engaging relation with the teeth of the ratchet wheel is by a spring 2i so as to prevent rotation of the ratchet wheel IS in a counter-clockwise direction.

It will be readily seen from the foregoing that upon energization of the electromagnet l2 the armature It will be pivoted in a clockwise direction in opposition to the force of the spring l8 causing the ratchet arm to engage the next succeeding tooth of the ratchet wheel it. At the extreme limit of movement of the armature l3 an actuating member 22 carried thereby engages the free end of a leaf spring 23 so 'as to open the contacts of a switch 24.

The opening of the switch 24 breaks the circult of the electromagnet I2, as will be explained hereinafter, causing de-energization of the electromagnet l2, whereupon the spring 88 actuates the armature E3 in a counterclockwise direction causing the pawl l5 to impart an increment of movement to the ratchet wheel I6 in a clockwise direction.

The ratchet wheel IB is connected through a .suitable shaft 25 indicated herein by dotted lines to switch arms, 28 and 21, and a cam 28.

The switch arms 26 and 21 are each arranged to contact in succession a series of contacts 25AL and TIA-L. .The switch arms 26 and 21 move from one contact to the next succeeding contact for each increment of movement imparted to the ratchet wheel l6 by the stepper relay l0 and upon one end of the switch arm moving out of contacting relation with the contact L the opposite end closes the contact A.

The switch contacts 26A--K are connected respectively through suitable electrical conductors to one terminal of corresponding load devices or electromagnets The opposite terminal of the electromagnets II are connected by an electrical conductor 3| to the negative terminal of a source of electrical energy 32 through a grounded connection.

The switch arm 23 is connected by a conductor 33 through a control switch 34 to the positive terminal of the source of electrical energy 32. The switch 34 controls contacts 34A-E. Contact 34A is open, while contacts 343 to E are connected to conductor 33.

The contact 23L is an open contact so that upon the switch arm 23 contacting the same, the circult to all of the load devices H are open for a purpose which will appear hereinafter.

The switch arm 21 is arranged to sequentially close contacts 21A-L connected to suitable resistor elements 33 which are in turn connected at the opposite end to conductor 33 for a purpose which will be explained hereinafter.

The shaft 25 also drives a cam 23 having portions 33 arranged to actuate an off normal switch 31 to an open position upon the switch arms 26 and 21 being positioned so as to close the respective contacts 23L and 21L. Upon the switch arms 23 and 21 being adjusted into contacting relation with one of the other contacts, the cam 28 permits the switch 31 to close for purposes which will be explained.

A relay winding 33 has one terminal connected by an electrical conductor 39 through the normally closed switch 24 and a conductor 43 to the positive terminal of the source of electrical en ergy 32. The opposite terminal of the winding 33 is connected by an electrical conductor 4| to an anode or plate 42 of an electronic valve 43.

The electronic valve 43 has cathodes 44, control grids 45, shield grids 43, heater or filaments 41 and the plates 42,

The cathodes 44 are connected by a conductor 48 to a manually operable selector switch 43 and through a conductor 53 to one contact of the of! normal switch 31. The opposite contact 52 is connected through the switch arm 31 and a grounded conductor 53 to the negative terminal 01 the source of electrical energy 32.

The switch 49 cooperates with switch contacts 49AE. A conductor 54 leads from the contact 49A to the conductor 4| so that upon switch arm 49 closing contact 49A the electronic valve 43 maybe effectively shunted.

Contact 493 may be connected through a push button switch 55 to the negative terminal of the source of electrical energy 32 through a grounded conductor 53. Thus upon switch 49 closing contact 493, the cathodes 44 of the electronic valve 43 may be directly connected to the negative terminal of the source of electrical energy 32 by closing the push button 55.

The remaining switch contacts 49C, 49D and 49E are connected to the negative terminal of the source of electrical energy 32 through a grounded conductor 51. Thus the cathodes 44 may be connected to the negative terminal of the source of electrical energy 32 by adjustment of switch 49 so as to close contacts 49C, 49D or 49E.

The electron flow from the cathodes 44 to the plates 42 is controlled by grids 45 connected by a conductor 53 to a plate 53 of a condenser 63. The opposite plate 3| of the condenser 33 is connected by a. conductor 32 to a contact 33A of a normally open switch 34 controlled by the electromagnetic relay winding 33. An opposite contact 33B is connected by a conductor 35 to the conductor 43 and thereby to the positive terminal or the source of electrical energy 32.

A conductor 33 leads from the conductor 32 to the relay winding I2 which is connected at its up.- posite terminal through a grounded conductor 31 to the negative terminal or the source of electrical energy 32,

Thus energization of relay winding 33 causes in turn relay H to be energized, whereupon switch 24 is actuated to an open position, thereby eflecting de-energlzation of winding 38, opening of switch 34 and de-energization of the stepper relay winding |2.

A switch arm 13 is connected by a conductor 11 to the conductor 33. The switch arm 13 cooperates with switch contacts 13A-E. The contacts 13A, 13B, 13C and 13D are open contacts, while the contact 1313 is connected by a conductor 11 to a second capacitor or condenser 13 connected by conductor 19 to the conductor 53 and across the capacitor 33 upon the closing of the switch contact 1313 so as to increase the capacity of the timing condenser.

A conductor 33 leads from the conductor 53 to the stepper relay switch arm 21. Thus the plate 59 of the capacitor 33 is connected by the conductors 53 and 33 to the switch arm 21 which, as previously described, is arranged to close sequentially the contacts 21A through L.

Leading from the contacts 21A through L, respectively, are the resistors 33A-L each of a value sufiicient to effect a. predetermined discharge period for capacitor 33 or time interval for energizing the load device corresponding thereto. The resistors 33A-L may be of difierent value so as to effect diflerent time intervals of operation for each load device.

Leading from the opposite terminals of the resistors 33A-L is the conductor 33. Connected to the conductor 33 by a conductor 3| is a switch arm 32 for cooperating with contacts 82A-E. The conductor 8| connects the switch arm 32 to the positive terminal of the source of electrical energy 32.

The switch arm 82 is arranged to selectively contact one of the five contacts including two open contacts 32A and 32C and three contacts 823, 82D and 82E connected by an electrical conductor 83 to the resistor 33L at a point intermediate the opposite ends of the latter resistor.

It will be seen then that when the switch arm 82 closes on'e of the contacts 323, 32D and 32E, a portion of the resistor 33 leading from the contact 21L will be shunted out of the circuit leading from the positive terminal of the source of electrical energy 32 and the plate 59 of the con: denser 33. However, upon the switch arm 32 contacting one of the open contacts 32A and 320, the full resistance of the resistor 33 leading from the contact 21L will be inserted in the latter circuit. r

The control switches 34, 49, 13 and 32 may be arranged for operation in unison from a single control or may be manually adjusted separately as desired.

Operation The foregoing electronic timer is particularly designed for use in conjunction with the manifold type of ice eliminating system for airfoil surfaces of aircraft and is arranged to open the boot inquence tor the proper time intervals. does not form at the same rate or to the same degree on all occasions, a certain flexibility of control has been incorporated to permit the operator to'vary certain components of the system to suit the prevailing conditions.

Referring to the drawing, and with the control switches in the position shown, operation is initiated by closing the push button 55; v The cathodes 41 are then connected through the push button 55 to the negative terminal of the source of electrical energy 32. The bias applied at the grids 45 is positive at the time the push button 55 is closed since the grids 45 are connected through the switch arm 'fl and contact 21L to the positive terminal of the source 32. Thus a large plate current flows effecting energization of the relay winding 38 causing switch 54 to close contacts 63A and 633. The closing of the switch 24 then effects a charging circuit for the capacitor 60 in which the electronic flow from the cathodes 44 to the grids 45 and through the conductors 58 applies a negative charge to the plate 59 of the capacitor 68, while a positive charge is applied to the plate 5| through conductor 62, switch 84, conductor 85 and conductor 40 to the positive terminal of the source of electrcal energy 32.

The closed relay switch 64 thus causes the condenser 58 to become quickly charged and in turn therelay winding l2 to become energized so as to open the switch 24 in the .plate circuit.

The opening of the interrupter switch 24 then cuts off the plate current, which de-energizes the relay winding 38 which opens switch 54 and the energizing circuit for the stepper relay winding l2. The spring l8 then draws the armature l3 downward in a counterclockwise direction and eil'ects movement of the ratchet gear I5 together with the stepper switches 26 and 21 to a position closing contacts 25A and 21A respectively and energizing circuit l IA.

Upon the opening of switch 64, the direction of electron flow relative to the condenser 68 reverses and the condenser 60 discharges. Thus, upon the opening of switch 84, there is an electron flow to the positively charged plate 5| the condenser 88 through grounded conductor 61, stepper relay winding [2, conductor, and conductor 52. The negatively charged plate 59 of the condenser 50 discharges through the conductor 58, conductor 88, stepper relay switch 21, contact 21A, resistance 35A, conductor 33 and through switch 34 to the positive terminal of the source 32.

The negative charge on the plate 58 of the condenser -88 applies a negative bias to the grids A through conductor 58 which is suilicient to keep the gritlbiased beyond cut of! for a predetermined perioddependent upon the value of the resistance 36 connected in the discharging circuit through operation of the stepper relay switch 21.

i The charge on the condenser 68 is thus gradually neutralized through the resistance 36 until the bias on the, grids 45 becomes sufliciently. positive to allow enough plate current to flow to again effect energization of relay winding 38 so as to close switch 64. The time required is dependent tarily by energization of the stepper relay l2 opening the circuit for the relay winding 38 and deenergizing the stepper relay l2 so as to cause the stepper switches 28 and 21 to advance to position 283 and 213 respectively. A new timing interval then begins during which circuit MB is energized.

Similarly the load circuits IIC-IIK ar energized for time intervals depending upon the value of the 'then connected resistor 38 and condenser 80. However, upon the stepper switch 21 moving to a position closing contact 21L, the cam 28 is adjusted so as to position the portion 35, as shown in the drawing, so as to open the of! normal switch 31, whereupon no power is then supplied to the cathodes 44. In order, to initiate operation with the control switch 48 in the position shown, the push button 55 must be pressed so as to complete the cathode circuit through the grounded connection 55 to the negative terminal of the source 32. As soon as the stepper switches 26 and 2": have moved to position A as described, the cam 28 is also adjusted so as to permit switch 37 to close contacts 5i and 52 and thereby connect the cathodes 44 through grounded conductor 53 to the negative terminal of the source 32. At the end of the cycle, cam 36 is adjusted through shaft 25 so as to once again actuate switch 31 so as to open the contacts 5| and 52.

If control switch 49 is adjusted so as to close contacts C, D or E, the cathodes 44 are connected through grounded conductor 56 to the negative terminal of the source 32 and hence in this position of control switch 49. the operation is continuous between cycles.

If control switch 82 be adjusted so as to close open contact 820, a high resistance 36L gives a d-well of, for example, approximately 60 seconds between cycles. if switch 49 closes contacts 49C, 49D or 49E. If control switch 82 be adjusted to close contacts 82D or 82E, the greater portion of resistor 36L is short circuited making the operation substantially continuous without dwell, provided, of course, switch 49 closes contacts 49C, 49D .or 49E. If in addition switch 15 be adjusted so as to close contact 15E. the additional condenser 18 is switched into the timing circuit and coacts with condenser 50 so as to increase all time intervals by a predetermined value of, for examplaiifty per cent.

In addition, the circuit has a homing characteristic, that is; if the control switch 49 be adjustedso as to close the contact49A during a timing cycle, the stepper switches 25 and 21 :will return without delay to the starting or L position. This is accomplished by the application of power directly through the off normal switch 31 and contact 49A to the relay 38 closing relay switch 64 and causing the stepper relay l2 to continuously operate the stepper switches 26 and 21 until the energizing circuit for the relay winding 38 is opened by the oil normal switch 31 at the end of the cycle of operation.

Although only one embodiment of the invention has-been illustrated and described, various changes in the form and relative arrangements of the parts, which will now appear to those skilled in the art, may be made without departing from the scope of the invention. Reference is, therefore, to be had to the appended claims for a definition of the limits of the invention.

What is claimed is:

1. A time delay circuit controlling apparatus comprising an electronic valve having an anode,

a cathode, and a control grid, a first electromagond switch element controlled by said second winding for opening the first circuit upon energization. of the second winding, and a discharging circuit for said. capacitor eifective'upon the opening of said first circuit.

2. The combination defined by claim lin which said charging circuit includes the cathode and grid of said electronic valve.

3. The combination defined by claim 1 in which said discharging circuit includes said second winding and additional means for retarding the discharge of said capacitor, whereby the control bias is applied to said grid for the time of said delay, and means ior varying said retarding a charging circuit for said capacitor and an energizing circuit for said second winding, a second switch element controlled by said second winding for opening the first circuit upon energization oi the second winding, a discharging circuit for said capacitor effective upon the opening of said first circuit, said discharging circuit including said second winding and resistor means for retarding the discharge of said capacitor, wherebythe control bias is applied to said grid for the time of said delay, and means varying said resistor means, said last mentioned means means, said last mentioned means controlled by said first and second windings.

4. The combination defined iby claim 1 in which said charging circuit includes the cathode and grid of said electronic valve, and the discharging circuit includes said second winding and additional means for retarding the discharge of said capacitor, whereby the control bias is applied to said grid for the time of said delay, and means for varying said retarding means, said last mentioned means controlled by said first and second windings.

5. A time delay circuit controlling apparatus comprising an electronic valve having an anode, a cathode, and a control grid, a first electromagnetic winding, a first circuit including said anode, cathode and first winding, a capacitor to supply a bias to said control grid upon discharging, a second electromagnetic winding, a switch element controlled by said first winding for closing operated by said second winding and controlled by said first winding.

6. A time delay c.rcuit controlling apparatus comprising an electronic valve having an anode, a cathode and a control grid, a first electromagnetic winding, a first circuit including said anode, cathode and first winding, a capacitor to supply a bias to said control grid upon discharging, a stepper relay, a switch element controlled by said first winding for closing a charging circuit for said capacitor and an energizing circuit ior said stepper relay, a second switch element controlled by said stepper relay for opening the first circuit upon energization of the stepper relay, a discharging circuit for said capacitor efiective upon the opening of said first circuit, and a plurality of load devices, said stepper relay sequentially closing energizing circuits for said load devices for time intervals dependent upon the discharge period of said capacitor.

7. The combination defined by claim 6 in which there is included a manually operable switch means for shunting said anode and cathode so as to effect energization of said first winding and undelayed operation of said stepper relay, and means actuated by said stepper relay for opening said shunt circuit upon said stepper relay reaching a home position.

JOHN WILLIAM muarcnmia 

